Wavelength-dependent nonlinear absorption and ultrafast dynamics process of WS2

Abstract

The nonlinear absorption and ultrafast dynamic process of WS2 nanosheets were investigated by using a broadband (ranging from 450 to 700 nm) nanosecond Z-scan technique. Z-scan measurements showed that WS2 nanosheets exhibit saturable absorption (SA), and the magnitude of SA is wavelength-dependent. Besides, the ultrafast dynamics process of WS2 was also investigated with femtosecond transient absorption spectrum. It was found that there is a double-exponential energy relaxation in the process. The investigation shows that WS2 nanosheets can be used for ultrashort pulse generation and a wide spectral range optical absorber.